Continued investigation of the anatomical organization of the avian brain in pursuit of a broader understanding of the general organization of vertebrate brains. Previous research in this laboratory has demonstrated the widespread common patterns of organization of the avian and mammalian visual and auditory pathways and their constituent neurons at all levels of the neuraxis. Parallel studies of the physiology and behavioral contributions of these structures have strongly supported these interpretations. Current studies are mainly concerned with the loci and patterns of primary and secondary projections of vestibular, trigeminal and vagal systems, and of the origin and termination of long descending telencephalic efferents. This research program provides a fundamental body of information concerning the anatomical organization of avian brains, but equally important provides a basis for further understanding of embryogenesis of vertebrate brains, evolution of brains, and possibly universal aspects of the organization of all vertebrate brains.